Extraction ofStreptococcal Type12M Protein by Cyanogen Bromide

Conditions fortherelease ofstreptococcal type12M protein fromwholecells bycyanogenbromide aredescribed; theydemonstrated thatmethionine isnot essential tothestructural arrangements whichaccount forsome ofitsimmunological andbiological properties. Thereleased M protein was separated from other proteins bycolumnchromatography withhydroxylapatite. Thetype-specific molecules whichreacted withprecipitating antibodies werefoundonlyinthe 0.3M eluate, formed zones withmobilities <12%ofthatofthedyefront on electrophoresis inthestandard acrylamide discgelsystem, formedatleast four bandsinsodiumdodecyl sulfate-acrylamide discgels withmolecular weights ranging from12,000 to23,000, andstimulated theformation ofopsonic antibodies inrabbits. Cyanogen bromide provides ahighly specific methodfortherelease of M proteins whichshould proveparticularly useful inanalyses ofstructuralfunctional relationships among different M proteins. M proteins arethemostimportant ofthe various cellular antigens ofgroup Astreptococci. Theyconfer aunique antiphagocytic property togroupA streptococci andareresponsible for thestimulation oftype-specific, opsonic antibod